Determination of Two-Phase Flow Rate Depth Distribution from Temperature and Pressure Profiles in Unconventional Gas Wells
Al-Rawahi, Hamza and Pereira, Sebastian
Engineering Honours Degree, 2013
University of Adelaide
Description The main objective of this project is to determine flow rate depth distribution from temperature and pressure profiles. Two phase gas-water mathematical model was developed and validated by three well data. The derived model includes mass and momentum balance for each phase and total energy balances of both phases in the well column. Temperature and pressure depth profiles from three production wells in field A (Australia) have been treated to determine the gas and water rates as well as water holdup from different layers in each well. .The results of surface rate measurement and tracer injection response (field A, Australia) show good agreement with the model predictions, which validates the method proposed and the model developed.
Application The proposed method and model have been successfully applied to the determination of gas and water rates from the measured well pressure and temperature data in three gas wells from unconventional field A (Australia). It allows recommending well stimulation for layers with low production rate of gas. It also assists with future well design based on the production rate of each layer in the reservoir.
Results and conclusions The inverse problem of determining the two-phase flow rates and water holdup has been solved by matching the pressure and temperature distributions with measured profiles along the well. A simple and robust solution is derived from the zero-order approximation of the original system for initial estimates of the two-phase flow rate distribution in the well. These estimates were used as initial guess for Runge-Kutta method which has been applied in the iterative numerical simulation. Good agreement between the measured and predicted pressure and temperature profiles as well as surface rate data from the three wells (field A, Australia) has been achieved.
Significance Determination of two-phase rate from different layers is important information for well stimulation. The well flow meters are cumbersome and expensive, and affect the flow in the well. It results in very low accuracy of rate measurements in unconventional gas reservoirs, like coal seam gas and shale gas fields. On the contrary, the well temperature and pressure sensors are small and low-cost chips. The presented method for predicting the rate profiles from the temperature and pressure data is proven to be effective and robust.